Circular RNAs (circRNAs) are small, non-coding RNAs in which the 5′ and 3′ ends are linked covalently by back-splicing of exons from a single pre-mRNA. More and more scientific evidence is gathered for their wide distribution in the animal world, playing the role of regulators for biological processes, being cell- and tissue-specific. They can influence cellular physiology by various molecular mechanisms, finally modulating gene expression. CircRNAs are believed nowadays to be expressed in both receptive and cancerous endometrium. Due to their abundant expression in the endometrial tissue and their small size and stability, they have been considered potential diagnostic markers and treatment targets for endometrial-related diseases. The regulation of proliferation and differentiation is essential for the formation of receptive endometrium and for endometrial cancer emergence and progression. The receptive endometrium can be regarded as the most highly differentiated state of the endometrium. In contrast, the cancerous endometrium is characterized by a high level of proliferation and the lowest degree of differentiation. These endometria could be conditionally considered opposites. We are investigating the circRNA–miRNA–mRNA regulatory networks that can promote or suppress the proliferation and differentiation of endometrial cells by activating specific signaling pathways in both receptive and cancerous endometria. It could be worth knowing whether there are universal endometrial switches responsible for proliferation and differentiation processes that can alter the balance between them. We are interested in their clinical application as biomarkers and therapeutic targets for both endometrial receptivity issues and EC cases, particularly in diagnosis, progression assessment, and outcome prediction.

INTRODUCTION: A diagnosis of lung function impairment in childhood is highly dependent on the respective reference values. Population differences in the pulmonary function of children have been frequently reported. The AIM of this study was to derive normal spirometric reference values for Bulgarian children and adolescents and to compare these results with other data set including our own reference equations developed 20 years ago. MATERIAL AND METHODS: Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and parameters of maximum expiratory flow-volume curves were measured in 671 healthy Bulgarian school children (339 males and 332 females) aged 7-18 years. Multiple linear regression analysis was performed for each spirometric parameter against age, height, weight, chest circumferences and fat free mass in both sexes. RESULTS: Excluding ratios, all measured spirometric parameters increased nonlinearly with age and height, and were significantly higher in boys than girls in adolescence. Height (H) explained the maximum variance for spirometric parameters and the best-fit regression equation relating functional parameters and body height was a power function (Y = a.Hb). FVC and FEV1 showed close correlations with height (r2 between 0.85 and 0.92), whereas the coefficients of determination for the flows were less close (r2 from 0.85 for PEF to 0.67 for MEF25%; always higher in boys). CONCLUSIONS: The developed prediction equations can be used in clinical practice. In comparison with reference equations based on European or USA populations, regional reference values are biologically more suitable for the interpretation of spirometric data.

Circular RNAs (circRNAs) are small, non-coding RNAs in which the 5’ and 3’ ends are linked covalently by back-splicing of exons from a single pre-mRNA. More and more scientific evidence is gathered for their wide distribution in the animal world, playing the role of regulators for biological processes, being cell and tissue-specific. They can influence cellular physiology by various molecular mechanisms, finally modulating gene expression. CircRNAs are believed nowadays to be expressed in both receptive and cancerous endometrium. Due to their abundant expression in the endometrial tissue and their small size and stability, they have been considered potential diagnostic markers and treatment targets for endometrial-related diseases. The regulation of proliferation and differentiation is important for the formation of receptive endometrium and for endometrial cancer emergence and progression. It may be worth investigating whether there are universal circRNAs-miRNAs-mRNAs regulatory networks that can promote or suppress the proliferation and differentiation of endometrial cells by activating specific signaling pathways in both receptive and cancerous endometrium.

The connection between the mother and the child has been considered one of the strongest bonds in nature. Though there are numerous factors that can influence the establishment of pregnancy, in its essence, three are considered major: a good quality embryo, a receptive endometrium, and successful cross-talk between them. The placenta, which derives from the trophoblast of the embryo, develops when a successful implantation occurs. It is an ephemeral organ through which the turnover of nutrients, gases, and waste molecules is realized. It serves as a barrier and can provide the embryo with immune factors. Placental disorders are observed in some rare but life-threatening obstetric conditions like preeclampsia (PE), fetal growth restriction (FGR), gestational trophoblastic diseases (GTDs), and gestational diabetes mellitus (GDM). The etiology and pathogenesis of some are still partially enigmatic. Our attention in this review was driven by the participation of small RNA molecules—miRNAs and piRNAs—as potential epigenetic modulators of genes that play a pivotal role in placental functioning. In this study, we analyze the influence of these epigenetic factors on the mechanisms of the development of preeclampsia. The molecular approach for understanding placental disorders may help new diagnostic and therapeutic solutions to be found.

Introduction: Bronchodilator response testing is performed in respiratory ill patients and reflects the airway structures and their possible changes after bronchodilator administration. Gold standard in the interpretation of the results are the established methods to assess the change in FEV1 and FVC and a change of >10% is considered a significant bronchodilator responsiveness (BDR). Aim: Since the BDR does not accurately differentiate between different types of airway diseases we aimed to determine whether additional spirometry parameters may contribute and have impact. Methods: We analyzed spirometry data from 60 hospitalized patients with a clinical diagnosis of asthma and COPD. A bronchodilator responsiveness testing was performed in all patients (33 female) aged 60.2±13.2 years. All patients completed slow and forced spirometry measurements including bronchodilator testing (BDT) with good efforts, complete exhalation, and FET ≥ 6 sec. Results: Among our group 25 patients had asthma and 35 patients were diagnosed with COPD. Applying the latest recommendation a significant bronchodilator responsiveness of >10% was found in 16 patients (27%). We measured and analyzed additionally the forced inspiratory flow (FIF) and the expiratory reserve volume (ERV) changes. A significant increase was found only in ERV but not always in combination with positive BDR. Conclusion: Bronchodilator response testing in clinical practice may be supported by the change in additional spirometry parameters. The reliability of the increased ERV found in different types of airway diseases needs further research.

Introduction: In post-COVID era we still have questions about the long term changes in the lung function and blood gas analysis of patients especially after severe form of Covid-19 pneumonia. The aim of this study is to evaluate those parameters and to investigate the recovery time of the patients. Methods: Patients underwent the following examinations between the second and sixth month after discharge: pulmonary function tests, blood gas analysis, and 6MWT. Results: 35 patients after severe form of Covid-19 pneumonia participated in the study. 57% of them had arterial hypertension, and the average BMI was 34. The most significant deviations were observed in the diffusion lung capacity with the main parameter - DLco. Decreased DLco<80% was observed in 73.5% of the patients. Subjectively, after submaximal effort, patients scored a mean value on the modified Borg scale, which corresponds to mild to moderate dyspnea. 25.7% of patients still had severe dyspnea after exercise. No significant correlation was found between DLco values and Borg scale score. A 6-minute walking test was performed to assess functional capacity and dyspnea. Oxygen saturation at rest was normal and after 6MWT it decreased to 89.5±3%, without significant desaturations and with a subsequent rapid recovery. However, the blood gas analysis showed normal pH and pCO2 values, but there was still a significant decrease in the PaO2 in 50% of patients. Conclusion: Recovery of diffusion capacity after disease is slow, and on the 6th month after discharge, the majority of patients still have reduced values. Although the saturation of all patients at rest remained normal, blood PaO2 values were significantly reduced in half of them.